Finely Dispersed Au Nanoparticles on SiO2 Achieved by the C60 Additive and Their Catalytic Activity

Abstract

AbstractWe have investigated in detail the effect of buckminsterfullerene (C60) additive on the structure and catalytic activity of Au/SiO2 catalysts prepared by a routine deposition–precipitation method employing HAuCl4 as the gold precursor. The structures of various catalysts have been characterized by using N2 adsorption–desorption isotherms, powder X‐ray diffraction, X‐ray photoelectron spectroscopy, transmission electron microscopy, photoluminescence, and Raman spectroscopy. The C60 additive was found to greatly enhance the dispersion of Au nanoparticles supported on SiO2. Supported Au nanoparticles that are about 3–5 nm in size can be synthesized without difficulty on C60/SiO2, whereas those sized about 7–10 nm are usually acquired on bare SiO2. Strong Au–C60 interaction with the charge transfer from Au nanoparticles to C60 has been observed in Au/C60/SiO2 and proven to suppress the agglomeration of supported Au nanoparticles and enhance their dispersion on SiO2. The catalyst Au/C60/SiO2‐10 (Au:C60 molar ratio of 10) exhibits a much better catalytic performance for CO oxidation than Au/SiO2, but is not active for CO oxidation at room temperature, which demonstrates that the intrinsic activity of supported Au nanoparticles increases with decreasing particle size, but supported Au 3–5 nm nanoparticles cannot activate oxygen for CO oxidation at room temperature. We propose that 3 nm is the critical size for Au nanoparticles to exhibit an intrinsic catalytic activity in CO oxidation at room temperature without additional contributions. These results provide novel and important insights into the fundamental understanding of intrinsic structure–activity relation of Au nanoparticles.